Apparatus and method for banding elongated cylindrical objects



July 10, 1962 J. G. BURNS 3,043,721

APPARATUS AND METHOD FOR BANDING ELONGATED CYLINDRICAL OBJECTS Filed Jan. 26, 1959 2 Sheets-Sheet 1 A l I 1 H gill L INVENTOR. JEROME G. BURNS ATTORN EY July 10, 1962 BURNS 3,043,721

APPARATUS AND METHOD FOR BANDING Filed Jan. 26, 1959 ELONGATED CYLINDRICAL OBJECTS 2 Sheets-Sheet 2 66 2 Fig. 2

I INVENTOR.

JEROME G. BURNS QM/W ATTORNEY United States Patent Filed Jan. 26, 1959, Ser. No. 789,188 10 Claims. (Cl. 117- 212) This invention relates to an apparatus and method, for banding elongated cylindrical objects. More particularly, this invention relates to an apparatus and method for coating a continuous length, cylindrical filament with longitudinally spaced cylindrical bands.

In the manufacture of film type electrical resistors which comprise an insulating core, usually of glass or ceramic, coated with a film of resistance material, such as carbon or a metal,'it is the practice to provide the coated core with a narrow cylindrical band of electrical conductive material, such as silver or gold, at each end thereof. Such bands act as terminations for the resistance film to which terminal wires or the like can be connected. The bands provide a good electrical connection between the terminal wires and the resistance film.

In the application for United States Letters Patent of Sidney J. Stein et al., Serial No. 385,066, filed October 9, 1953, now US. Pat. No. 2,958,899, entitled Apparatus for and Method of Deposition of Solids From Vapors,

and Products Produced Thereby, there is disclosed a method of making film type electrical resistors by coating the resistance material film on a single continuous length glass or ceramic rod or tube filament of small diameter. After being coated, the filament is cut into the individual resistance elements. It is desirable to apply the terminating bands to the coated filament while the filament is still a single continuous length since it is very difiicult to handle the small individual resistance filaments. How ever, the bands applied to the filament must have sharp circular ends and must be uniformly spaced apart so that the resistance elements cut from the filament are all of uniform resistance value.

'-It is an object of the present invention to provide an apparatus and method for applying longitudinally spaced, cylindrical bands to a continuous length filament.

It is another object of the present invention to provide an apparatus and method for applying longitudinally spaced, cylindrical bands to a continuous length filament which have sharp circular ends, and which are uniformly spaced apart.

\ It is a further object of the present invention to provide an apparatus and method for applying terminating bands to a continuous length filament coated with a resistance material. I I

Other objects will appear hereinafter.

For the purpose of illustrating the invention there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumen- A plicator device of the present invention looking in the direction of arrows 44 in FIGURE 2.

FIGURE 5 is a side elevational View, partly sectioned, of a portion of the applicator wheel of the band applicator device of the present invention.

FIGURE 6 is a top elevational View of one of the applicator wheel teeth.

Nice

FIGURE 7 is a sectional view taken along line 7-7 of FIGURE 5.

FIGURE 8 is a transverse sectional view of a transfer wheel of the band applicator device of the present invention.

Referring initially to FIGURE 1, the banding assembly of the present invention comprises a band applicator de-- vice, generally'designated as 10, a dryer, generally designated as 12, and a curing oven, generally designated as FIGURES 2, 3, and 4 show the band applicator device 10 in detail. Band applicator device 10 comprises a horizontal supporting plate 16 mounted on a base 18. Bolts 20 are threaded through the supporting plate 16 adjacent the corners ofthe supporting plate 16, and engage the top surface of base 18. A separate lock nut 22 is threaded on each of the bolts 20, and engages the top surface of the supporting plate 16. Cap screws 24 extend'through the supporting plate 16 adjacent the corners of the supporting plate 16, and are threaded into the base 18. Cap screws 24 hold the ends of bolts 20 against the to surface of the base 18. By adjusting bolts 20, supporting plate 16 can be leveled for proper operation of the band applicator device 10.

A rectangular mounting plate 26 is supported in an upright position on the supporting plate 16. A pair of braces 28 are secured to the supporting plate 16 and to the back of the mounting plate 26 along opposite ends vertically. Mounting plate 26 is divided horizontally into a bottom section 26a and a separate top section 26b. A

pair of arms 36 are secured to the ends of the top section 2615 of mounting plate 26. Arms 30 extend vertically downwardly across the ends of the bottom section 26a of mounting plate 26.' A pair of pins 32 are tightly secured in holes 34 in the ends of the bottom section 26a of mounting plate 26 adjacent the top of the bottom section 26a. Pins 32 project beyond the ends of bottom section 26a of mounting plate 26, and extend through holes 36 in arms 30. Holes 36 are slightly larger in diameter than the diameter of pins 32 so that the arms 30 can pivot on the pins 32. Each of the arms 30 has a flange 38 secured to its bottom end which extends across the front of the bottom section 2642 of mounting plate 26.

A pair of clamps 40 are mounted on the front of the bottom section 26a of mounting plate 26 adjacent the flanges 38 of arms 30. Clamps 40 may be of any type clamp by which the flanges 38 can be releasably clamped against the front of the bottom section 26:; of mounting plate 26. The clamps 40 shown each includes a clamping tip 42 which extends over a flange 38, and a handle 44. The handle 44 is connected to the clamping tip 42 through a linkage so that when the handle 44 is pressed toward the bottom section 26a of mounting plate 26, the clamping tip 42 is urged against the flange 38 to clamp the flange 38 against the bottom section 26a of mounting plate 26. This secures the top section 26b of mounting plate 26 in direct vertical alignment with the bottom section 26.of mounting plate 26. When the handle 44 is pulled away from the bottom section 26a or mounting 'plate 26, the clamping tip 42 is moved away from the flange 38 so that the arms 30 are free to pivot on the pins 32 to swing the top section 26b of mounting plate 26 at an angle to the bottom section 26a.

A filament drive roll 46 is mounted on a shaft 4 8 juxtaposed to the front of the top section 26b of mounting plate 26, andadjacent one end of the top section26b. A ring 50 of hard rubber is secured around the outer periphery of the drive roll 46. Shaft 48 extends through and is rotatably mounted on the top section 26b of the mounting plate 26. A sprocket wheel 52 is mounted on the shaft 48juxtaposed to the back of the top section is only slightly spaced from the rubber ring 50 of drive roll 46;

- An applicator wheel 60 is mounted on a shaft 62 juxtaposed to the front of top section 26b of mounting plate 26, and adjacent the other end of the top section 26b. Shaft 62 extends through and is rotatably mounted on the top section 26b of mounting plate 26. A sprocket wheel 64 is mounted on the shaft 62 juxtaposed to the back of the top section 26b of mounting plate 26 (see FIGURE 3). Applicator wheel 60 has a plur'alityof circumferentially spaced teeth 66 extending radially outwardly from the periphery of the applicator wheel 60. Each tooth 66 has a semicircular groove 68 in its'outer surface (see FIGURES 5, 6, and 7). Groove 68 extends transversely between the sides of the tooth 66, and its of a radius equal to the radius of the filament on which the bands are to be applied. The surfaces 70 of tooth66 on both sides of the groove 68 are tapered radially inwardly and away from the groove 68; Tooth 66 has an arcuate groove 72- in each of its end surfaces, which grooves 72 extend across the ends of the groove 68. Grooves 72 extend radially along the entire height-of the end surfaces of the tooth 66. The teeth 66 are uniformly spaced around the periphery'of' the applicatorlwheel 60. Thus, the number of teeth 66 on the applicator wheel 60 determines the spacing between the teeth 66, and thereby determines the spacingbetween the bands applied to the filament. A second applicator wheel 74- is mounted on a shaft 76. juxtaposed to the front of the bottom section 2611 of mounting plate 26. Applicator wheel 74 is identical to applicator wheel 60, and has a plurality of circumferentially spaced teeth 78 which are identical to the teeth 66 of applicator wheel 60. Shaft 76 extends through and is rotatably mounted on the bottom section 26a of mounting plate 26.- 'A sprocket wheel 30 is mounted on the shaft 76 juxtaposed to the back of the bottom section 26a of mounting plate '26. Shaft 76.is offset slightly from a vertical line passing through the shaft 62, so, that" the line passing through theaxes of the shafts 62 and '76 is at a slight angle, approximately ten degrees, with respect to the vertical. Shaft 76 is spaced from the shaft 62 a distance such that the outer peripheral circles of the teeth 66 of applicator wheel 60 and the teeth 78 of applicator wheel 74 both are tangent to a common horizontal line.

- Applicator wheels '60 'and 74 are positioned so that the horizontal line to which the peripheral circles of the teeth '66 and 78 are.tangent passes between the peripheries of the; drive vwheels 46 and 54.

Y A transfer wheel. 82 is mounted on a shaft 84 juxtaposed to the front of top section 26b of mounting plate 26. Shaft 84' extends through and is rotatably mounted on the top section 26b of mounting plate 26. A sprocket f wheel 86 is mounted onthe shaft 84 juxtaposed to the back of the topsection' 26b of mounting plate 26 (see section26b of mounting plate 26 .beneath the transfer wheel 82'. Reservoir cup 8-8 has a reservoir recess 90 in its upper surface through which the periphery of the coated on its surface with a resistance material.

4 transfer wheel 82 passes. A bracket 92 is mounted on the reservoir cup 88 at the side of the transfer wheel 82 opposite the applicator wheel 60.. Bracket 92 has a flange 94 extending vertically upwardly therefrom. A

flexible rod 96 is secured to the bracket 92 and extends 'vertiaclly upwardly'therefrom between the flange 94 and the transfer wheel 82. A doctor blade 98 is mounted on the upper end of the flexible rod 96. Doctor blade 98 has a substantially V-shaped notch, not shown, in its forward edge through which the periphery of the transfer wheel 82 passes.

96. Screw 100 permits adjustment of the position of the doctor blade 98 with respect to the surface of the transfer wheel 82.

A second transfer wheel 102, which is identical to transfer wheel 82, is mounted on a shaft 104 juxtaposed to the front of the bottom section 26a of mounting plate 26, and below the applicator wheel 74. Shaft 104 extends through and is rotably mounted on the bottom section 26a of, mounting plate 26. A sprocket wheel 106 is mounted on shaft 104 juxtaposed to the back of the bottom section 26a of mounting plate 26. Transfer wheel 102 is positioned so that its periphery passes through and contacts the surface of the grooves in the outer surface of the teeth 78 of applicator wheel 74.

A reservoir cup 108, similar to reservoir cup 88, is mounted on the front of the bottom section 26a of mounting plate 26 below the transfer wheel 102. Reservoir cup 108 has a reservoir recess 110 in its upper surface through which the periphery of transfer wheel 102 passes. A bracket 112 is mounted on the reservoir cup 108 to one side of the transfer wheel 102. Bracket 112 has a flange 114 extending vertically upwardly therefrom.

' A flexible rod 116 is secured to the bracket 112 and extends vertically upwardly therefrom between the flange.

114 and the transfer wheel 102. A doctor blade 118, similar to doctor blade 98, is secured to the top of the flexible rod 116. A screw 120 is threaded through the top end of flange H4 and engages the flexible rod 116.

As shown in FIGURE 3, an endless chain 122 extends around the sprocket wheels 52, '86, 64, 80, and'106, to

rotate the sprocket wheels in unison. Endless chain 122 passes around the sprocket wheels in such a manner that sprocket wheels64 and 80. will be rotated in opposite directions, sprocket wheels 64 and 86 will be rotatedin opposite directions, sprocket wheels 80 and 106 will be rotated in opposite directions, and sprocket wheels 64 and 52 will be rotated in the same direction. Thus, applicator wheels 60 and 74 will be rotated in opposite directions, the transfer wheels 82 and 102 will be rotated in directions opposite to their respective applicator wheels 60 and 74,

and applicator wheel 60 will be rotated in the same direction as drive roll 46. As shown in FIGURE 4, shaft 104 e has a second sprocket wheel 124 mounted thereon 'in tandem with sprocket wheel 106. An endless drive chain 126 connects the sprocket wheel 124 to a source of power, not shown.

The banding apparatus of the present invention'operates to' apply longitudinally spaced cylindrical bands onto an elongated filamentin the following manner:

The filament 128 (see FIGURE 1) is first placed between the drive rolls 46 and '54 and between the applicator wheels 60 and 74 of the band applicator device 10. For making electrical resistors of the type described in the previously mentioned patent application Serial No. 385,066 of Sidney J. Stein at e1., the filament 128 comprises an elongated rod or tubeof glass or ceramic However, the filament 128 may be any other type of filamentary material, such as an insulated wire, on which it is desired to provide spaced bands, such as for coding purposes. The filament 128 is placed between the drive rolls 46 and 54, and the applicator wheels 60 and 74 by pulling out on the handles 44 of clamps 40 to release the clamp- A screw 100 is threaded through theupper end of the flange 94, and engages the flexible rod ing tips 42 of the clamps 40 from the flanges 38 of arms 30. The arms 30 are then pivoted about the pins 32 to swing the drive roll 46 and applicator wheel 60 away from the drive roll 54 and applicator wheel 74 respectively. The filament 128 can then be placed onthe drive roll 54 and in the grooves in the outer ends of the teeth 78 of applicator wheel 74. The arms 30 are then swung back to bring the drive roll 46 and the applicator wheel 60 over the filament 128. Handles 44 of clamps 40 are pressed inwardly to clamp the flanges 38 of arms 30 tightly against the front of the bottom section 26a of mounting plate 26. The filament 128 is then held between the outer peripheries of drive rolls 46 and 54, and extends through the grooves in the outer surfaces of the teeth 66 and '78 of the applicator wheels 60 and 74.

The source of power is turned on to rotate shaft 184 through drive chain 126 and sprocket wheel 124. This also rotates the shafts '48, 62, 76, and 84 through the endless drive chain 122. The movement of the drive chain 126 is directed so that the drive roll '46 is rotated in the direction of arrow 130 in FIGURE 1. Since the drive roll 46 frictionally engages the filament 128, the rotation of the drive roll 46 moves the filament 128 longitudinally toward the applicator wheels 68 and 74. Drive roll 54 supports the filament 128 and is rotated by the longitudinal movement of the filament 128.

As the transfer wheels 82 and 102 are rotated, the peripheries of the transfer wheels 82 and 102 pass through the reservoir recesses 90 and 110 in the reservoir cups 828 and 108 respectively. The reservoir recesses 90 and 110 are filled with the material to be applied to the filament 128. For applying terminating bands to an electrical resistance filament, the material in the reservoir recesses 90 and 110 may be a resinate of an electrical conducting metal, such as silver or gold, dissolved in a solvent so as to be in liquid form. However, for applying bands to other types of filamentary material, the material in the reservoir recesses 90 and 110 may. be a paint or an ink. As the peripheries of the transfer wheels 82 and 102 pass through the reservoir recesses 90 and 110, they are coated with the material in the reservoir recesses 90 and 114 As the coated peripheries of the transfer wheels 82 and 102 rotate further, they pass across the doctor blades $8 and 118 respectively, which scrapes the excess material from the transfer wheels 82 and 102. As the transfer wheel 82 rotates further, the coated periphery of the transfer wheel 82 passes through the grooves 68 in the end surfaces of the teeth 66 of transfer wheel 60. The periphery of the transfer wheel 82 engages the surfaces of the grooves 68 in the teeth 66 so as to transfer'the material coated on the transfer wheel 82 to the surfaces of the grooves 68. Thus, each of the grooves 68 in the teeth 66 of applicator wheel 60 is coated with the material to be applied to the filament 128. In the same manner, transfer wheel 102 coats the surfaces of each of the grooves inthe outer end of the teeth 78 of applicator wheel 74 with the material to be supplied to the filament 128.

As previously stated, the filament 128 extends through the grooves in the outer surfaces of the teeth 66 and 78 of the applicator wheels 60 and 74, which grooves extend halfway around the filament 128. Thus, as the drive roll 46 moves the filament 128 longitudinally between the applicator wheels 60 and 74, and the applicator wheels 60 and 74 are rotated, the coated surfaces of the grooves in the outer surfaces of the teeth 66 and 78 engage the outer surface of the filament 128 and apply the longitudinally spaced bands 132 thereon. Since the applicator wheel 74 is offset from the applicator wheel 60, the teeth 78 of the applicator wheel 74 engage the unbanded filament 128 first to apply the lower half of the bands 132 to the filament 128. The teeth 66 of applicator wheel 60 then engage the filament 128 directly over the bottom halves of the bands 132 to apply the upper halves of the bands 132 and thus complete the bands 132 (see FIGURE 1). This permits the filament 128 to be simultaneously contacted by the teeth of both applicator wheels 60 and 74 without the filament 128 being crushed because of variations in the diameter of the filament 128.

As shown in FIGURE 6, the grooves in the end surfaces of the teeth 66 and 78 of the applicator wheels-60 and 74 are each wider at their sides than at their bottom because of the grooves in the ends of the teeth. Thus, the bands 132 are longer at the sides of the filament 128 than along the top and bottom of the filament 128. It has been found that when the material of the bands 132 is applied to the filament 128, the material has a tendency to flow longitudinally along the filament 128' while the material is still wet. It has also been found that the material of the bands 132 flows more at the top and bottom of the filament128 than along the sides of the filament 128. Thus, by applying to the filament 128 bands which are shorter at the top and bottom of the filament 128 than along the sides of the filament 128, the material of the bands will flow to an extent to provide the bands 132 with sharp circular ends. Since different materials may flow different amounts, the depth of the grooves in the ends of the teeth 66 and 78 of the applicator wheels 60 and 74 will vary with the particular material being coated on the filament 128, and must be determined experimentally for the particular material being used.

After the bands 132 have been applied to the filament 128, the banded filament 128 passes over the dryer 12. Dryer 12 comprises a funnel 134 having a blower 136 and a heater 138 therein. Blower 136 forces air across the heater 138, and the heated air passes through the funnel 134 onto the banded filament 128. The heated air removes some of the solvents from the material of the band 132' and thereby dries and fixes the material of the bands 132.

The banded filament 128 then passes through the oven 14 which is heated to a temperature to completely cure the material of the bands 132. If the bands 132 are terminating bands or an electrical resistance filament, the oven 14 is at a temperature whichconverts the metallic resinate to the electrical conductivev metal.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, referenceshould be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

I claim:

1. Apparatus for applying longitudinally spaced bands on a continuous length filament comprisinga vertical mounting plate, a pair of shafts extending through and rotatably mounted on said mounting plate, a separate applicator wheel mounted on each of said shafts juxtaposed to one side of said mounting plate, said applicator wheels being identical and having a plurality of circumferentially spaced teeth extending radially from their outer peripheries, each of the teeth of said applicator wheels having a semi-cylindrical groove in its circumferential outer surface, said grooves extending across the entire circumferential length of the outer surface of said teeth, each of the radial end, surfaces of each of said teeth having'a groove extending radially alongsaid end surface and extending across the end of the groove in the outer surface of the tooth, said applicator wheels being mounted in the same plane with the circles of the outer surfaces of the teeth of the wheels being on opposite sides of and substantially tangential to a straight horizontal line, a second pair of shafts extending through and rotatably supported on said mounting plate, a separate drive roll mounted on each of the shafts of said second pair juxtaposed to said one side of said mounting plate, said drive rolls being in substantially contacting relation and on opposite sides of the horizontal line passing between said applicator wheels, common means for simultaneously rotating said applicator wheels and one of said drive rolls, and means for applying a liquid coatmeans for applying a coatingmaterial'to the surfaces of the grooves in the teeth of said applicator wheels comprises a separate transfer wheel adjacent each of saidapplicator Wheels with the periphery of the transfer wheels extending through and contacting thesurface of the grooves in the outer surface of the teeth of the applicator wheels, each of said transfer wheels being mounted on'a separate shaft which extends through and is rotatably mounted'on said mounting plate, a separate reservoir cup mounted on said mounting plate beneath 'each'of said transfer wheels, each of said reservoir cups plicator wheels.

3. Apparatus in accordance with claim 2 in which the means for simultaneously rotating the applicator wheels,

transfer wheels, and one of the drive rolls comprises a separate sprocket wheel mounted on each of the shafts carrying said applicator wheels, transfer wheels, and said one drive roll, said sprocket wheels being juxtaposed to the other side of said mounting plate, and an endless drive chain connecting said sprocket wheels.

- 4. Apparatus in accordance with claim 1 in which the axis of rotation of one of said applicator wheels is horizontally offset from the axis of rotation of the other applicator wheel sothat the teeth of said one applicator wheel engages the filament before the teeth of the other applicator wheel andthe wheels are angularly positioned so that each tooth on the other applicator wheel engages the same longitudinal portion of the filament as a tooth of the one applicator wheel so that the coatings applied to the filament by the teeth form'cylindrical bands around the filament.

5. Apparatus in accordance with claim 1 in which said mounting plate is divided horizontally into a top section and a bottom section, one of each of said applicator -'wheels, transfer wheels, and drive rolls being mounted mounting plateon the bottom section comprises a pair of arms secured to the ends of said top section and extending vertically downwardly along the ends of said bottom section; a separate pin projecting from each end of said 'bottom section, said arms being pivotably mounted on said pins,'a separate flange secured to the bottom end of each of said arms and'extending across a side of said bottom section, and a pair of clamps mounted on the bottom section and releasably engaging said flanges to secure the top section in direct vertical alignment with said bottom section.

7. Apparatus for-applying longitudinally spaced bands on a continuous length filament comprising a support, a.

pair of identical applicator Wheels rotatably mounted on said support, each of said applicator Wheels having a plurality of ci'rcum-ferentially spaced teeth extending radiallyv from its outer periphery, each of the teeth of said wheels having a semi-cylindrical groove in its circumferential outer surface extending across the entire circumferential length of the outer surface, each of the radial end surfaces of each of said teeth having a groove extending radially along said end surface and extending across the end of the groove in the outer surface of the tooth, said wheels being mounted in the same plane with the circles of the outer surfaces of the teeth of the wheels being on opposite sides of and substantially tangential to a straight line, means for rotating said wheels,

means for applying a liquid coating material to the surfaces of the grooves in the outer surface of the teeth of said wheels, and means for moving the filament between the wheels and through the grooves in the outer surfaces of the teeth of the Wheels.

8. Apparatus in accordance with claim 7 in which the axis of rotation of one of said applicator wheels is olfset from the axis of rotation of the other applicator wheel so that the teeth of said one applicator wheel engage the filament before the teeth of the other applicator wheel, and the wheels are angularly positioned so that each tooth on the other applicator wheel engages the same longitudinal portion of the filament as a tooth of the one applicator Wheel so that the coatings applied to the filament by the teeth form cylindrical bands around the filament. Y

9. A method of applying longitudinally spaced band on a continuous length filament which comprises continuously moving said filament horizontally in the direction of its length, applying at longitudinally spaced intervals along the filament cylindrical coatings of a liquid material which coatings are longer along the sides of the filament than alongthe top and bottom of the filament,- permitting the material of the coatings to flow longitudinally along the filament to an extent to provide the coatings with sharp circular ends, drying the coatings, and then curing the coatings.

10. A method of applying longitudinally spaced bands on a continuous length filament which comprises continuously moving said filament horizontally in the direction of its length, applying atlongitudinally spaced intervals along the filament coatings of a liquid material which extend half way around the circumference of the filament, applying coatings of the liquid material around the other half of the circumference of the filament between the ends of the first coating, said coatings being longer along the sides of the filament than along the top andbottom of the filament, allowing the coatings to flow longitudinally along the filament to provide the coatings with sharp circular ends, drying said coatings, and then curing said coatings.

References Cited in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR APPLYING LONGITUDINALLY SPACED BANDS ON A CONTINUOUS LENGTH FILAMENT COMPRISING A VERTICAL MOUNTING PLATE, A PAIR OF SHAFTS EXTENDING THROUGH AND ROTATABLY MOUNTED ON SAID MOUNTING PLATE, A SEPARATE APPLICATOR WHEEL MOUNTED ON EACH OF SAID SHAFTS JUXTAPOSED TO ONE SIDE OF SAID MOUNTING PLATE, SAID APPLICATOR WHEELS BEING INDENTICAL AND HAVING A PLURALITY FROM THEIR CUMFERENTIALLY SPACED TEETH EXTENDING RADIALLY FROM THEIR OUTER PERIPHERIES, EACH OF THE TEETH OF SAID APPLICATOR WHEELS HAVING A SEMI-CYLINDRICAL GROOVES IN ITS CIRCUMFERENTIAL OUTER SURFACE, SAID GROOVES EXTENDING ACROSS THE ENTIRE CIRCUMFERENTIAL LENGHT OF THE OUTER SURFACE OF SAID TEETH, EACH OF THE RADICAL END SURFACES OF EACH OF SAID TEETH HAVING A GROOVE EXTENDING RADIALLY ALONG SAID END SURFACE AND EXTENDING ACROSS THE END OF THE GROOVE IN THE OUTER SURFACE OF THE TOOTH, SAID APPLICATOR WHEELS BEING MOUNTED IN THE SAME PLANE WITH THE CIRCLES OF THE OUTER SURFACES OF THE TEETH OF THE WHEELS BEING ON THE OPPOSITE SIDES OF AND SUBSTANTIALLY TANGENTIAL TO A STRAIGHT HORIZONTAL LINE, A SECOND PAIR OF SHAFTS EXTENDING THROUGH AND ROTATABLY SUPPORTED ON SAID MOUNTING PLATE, A SEPARATE DRIVE ROLL MOUNTED ON EACH OF THE SHAFTS OF SAID SECOND PAIR JUXTAPOSED TO SAID ONE SIDE OF SAID MOUNTING PLATE, SAID DRIVE ROLLS BEING IN SUBSTANTIALLY CONTACTING RELATION AND ON OPPOSITE SIDES OF THE HORIZONTAL LINE PASSING BETWEEN SAID APPLICATOR WHEELS, COMMON MEANS FOR SIMULTANEOUSLY ROTATING SAID APPLICATOR WHEELS AND ONE OF SAID DRIVE ROLLS, AND MEANS FOR APPLYING A LIQUID COATING MATERIAL TO THE SURFACES OF THE GROOVES IN THE TEETH OF SAID APPLICATOR WHEELS. 